MySQL Activity 1

8/14/2019 MySQL Activity 1

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Laboratory Activity 1

MySQL Basics

Objectives

At the end of the activity, student is expected to perform the following:

Run MySQL command line Display available databases Create database and tables Alter table and set up primary key Insert, update and delete tables

Run MySQL Command Line Prompt

We run MySQL prompt, click Start | Programs | MySQL | MySQL Server 5.1 | MySQLCommand Line Client. See Figure 1. If you are prompted with a password, type the

password that you have assigned during running of MySQL Server Instance Config Wizardor simply hit enter from keyboard.

Figure 1. Launching of Command Prompt Window


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Figure 2 shows the mysql command prompt line . You are now on MySQL Serverenvironment.

Figure 2. MySQL command prompt

Display Available Databases

MySQL comes with default databases upon installation. These are information_schema,mysql and test. Mysql and information_schema databases are special databases where

MySql server stores various access permissions. Test database is used for various testingfeatures and sample databases.

To display all the available databases on the server we type:

SHOW DATABASES;

Please take note that all commands should be terminated with semicolon to signal

MySQL that a command is completed and ready for execution. Figure 3 should show theoutput of the command.

Figure 3. Databases available currently at server


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Create Database

We will now create our own (new) database. Let us say that the name of our database is

my_store. Command syntax for creating database is CREATE DATABASE . Figure 4 displays the creation of my_store database after issuing the SHOWDATABASES command.

Figure 4. my_store database is created

Create Table within the Database

Database consists of table/s where we store rows and columns. Creating a database does not

mean you open it automatically. USE is the syntax in opening a database.In order to open my_store database we issue:

USE my_store;

We will create now a table products to hold all products data within the database.Our products table consists of attributes/fieldnames vital in identifying description about a

product. Syntax in creating a table has this format:

CREATE TABLE ( DATA TYPE, DATA TYPE

DATA TYPE);

Our initial table attributes for products are productID, description and unit.We issue this command to create our first table:

CREATE TABLE products ( productID VARCHAR(5),

description VARCHAR(50), unit VARCHAR(3));


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To check the structure ofproducts table, we use DESCRIBE to show

its composition. Figure 5 has the output:

Figure 5. Creating a Table

Alter Table and Set up Primary Key

All relational database tables should have a primary key/s that will identify uniqueness of

row/record. On our products table, we will set productID as the primary key. We issue

the following command:

ALTER TABLE products

ADD PRIMARY KEY (productID);

What you have noticed here is the use of ADD PRIMARY KEY command in setting

up the productID as our primary key. As we again describe the structure of our table, Figure6 shows the output:

Figure 6. Setting up of productID as primary key


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We may even add additional columns/attributes that will further describe data for

products. Let us add column date_created on our table.

ALTER TABLE products

ADD date_created DATE;

Describing the table again after the ALTER command shows on Figure 7.

Figure 7. Adding date_created column

The INSERT Command

The INSERT INTO statement is used to insert new rows/records into a table. After theVALUES keyword, a comma-separated list of column names follows:

INSERT INTO (, .)

VALUES (


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SELECT * FROM products;

Figure 8 shows the output of the two rows insertion upon displaying it with SELECT

statement:

Figure 8. Display of records after a SELECT statement

Using UPDATE statement

This command is used to modify the data in the table. It has the following syntax:

UPDATE SET = new_value

WHERE < where condition> ;

If we want to correct PC002s Description to a value Dell laptop computer, ourstatement will be:

UPDATE products

SET description=Dell laptop computer

WHERE productID = PC002;

We have used WHERE clause in the statement to qualify what data is to be modified,

thereby limiting the scope of the update.

Again, SELECT statement is used to display changes. See Figure 9.


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Figure 9. Using UPDATE statement

Deleting Records from Table

The DELETE statement is used to delete rows from table and returns the number of rowsdeleted. Below is the syntax that uses also a WHERE clause to identify the criteria of what

data should be removed:

DELETE FROM WHERE < where condition>;

Let us delete productID which has a value of PC001.

DELETE FROM products

WHEREproductID = PC001

;

We issue again a SELECT statement to see the deletion was done. Figure 10 shows

it.

Figure 10. Issuing a DELETE statement.

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MySQL Activity 1